MS-4 What is a Watershed?

Within a given area of land that is bordered by high points (such as hills and mountains), all storm water will naturally tend to run toward a common low point. This runoff water flows to lakes, rivers, wetlands, or filters its way into the groundwater.

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South Annville Township, located in the southwestern part of Lebanon County, lies within the Chesapeake Bay Watershed, which is actually the largest watershed on the Atlantic Seaboard of North America. Runoff water within this enormous drainage basin (over 64,000 square miles!) works its way downstream via more than 150 major streams and rivers, eventually making its way into the Chesapeake Bay.

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There are over 2,000 watersheds in the continental United States. Because runoff water carries pollution along with it, we encourage you to learn more about watersheds and what you can do to help keep water clean for people, wildlife, and vegetation in your community and downstream.